Simplify the following expression: $12\sqrt{18}$.
Answer: First, try to factor a perfect square out of the radical. $= 12\sqrt{18}$ $= 12\sqrt{9 \cdot 2}$ Separate the radical and simplify. $= 12\sqrt{9} \cdot \sqrt{2}$ $= 12 \cdot 3 \cdot \sqrt{2}$ $= 36\sqrt{2}$